All time? 4n0nym1str3ss, period, no contest.
I do have a strong liking towards N1kk1 F4t4|3 as many others do, her voice, her style, she rings all the right bells and pushes precisely the right buttons for me and many others.
Honorable mentions: Soforia, Lady Jennifahr, Lady Ru'etha, Trance (Emma Evans), that's really about it for me personally. The rest just don't do anything for me at all, they're either just not talented enough, or their voices grate me the wrong way for whatever reason. For me it's really about the voice, I don't give a fuck about gimmicks like reverb, background music, binaurals (useless and have zero effect on me), etc.
Yes, some of the ones I just mentioned do use some reverb now and again, and some background music, but the draw for me isn't just they hypnosis aspects, it's the voice, so if the voice catches me that's all it takes 'cause I will hyper-focus on that and that alone above and beyond the gimmicks used.
There's literally a hundred or more "hypnodommes" out there nowadays and I've sampled pretty much every one of 'em, you folks can have 'em. I really wish N1kk1 F4t4|3 was still making files, hell I wish 4n0nym1str3ss was still around too - there's been rumors over the years that 4n0nym1str3ss aka Vindaloo MacKenzie passed away in some camping or climbing accident but to this day I've still never been able to lock down a 100% confirmation on that.
Regardless, if I was a wealthy man and had the ability I'd be offering large sums of money for either of those ladies to make more content. :)
I saw an article in the recent past that said at some point there's going to be voice recognition software that can sample someone's voice with a variety of audio files and then generate a very close approximation of it, which if true is something I'm highly interested in. Would be awesome to provide it a lot of recordings from 4n0nym1str3ss or N1kk1 or however and then have it become a text-to-speech engine in their voices, that would be fucking amazing to make use of. :)